From WordNet (r) 3.0 (2006) [wn]:
unbalance
n 1: a lack of balance or state of disequilibrium; "a hormonal
imbalance" [syn: imbalance, instability, unbalance]
[ant: balance]
2: a state of mental disturbance and disorientation [syn:
derangement, mental unsoundness, unbalance]
v 1: throw out of balance or equilibrium; "The tax relief
unbalanced the budget"; "The prima donna unbalances the
smooth work in our department" [ant: balance,
equilibrate, equilibrise, equilibrize]
2: derange mentally, throw out of mental balance; make insane;
"The death of his parents unbalanced him" [syn: unbalance,
derange]